Incipient Transcalvarial Cerebral Herniation: Underrecognized Complication of Elective Craniotomy Hitesh Kumar Gurjar, Shashwat Mishra, Kanwaljeet Garg INTRODUCTION The compulsions of the Monroe-Kellie doctrine in the confined cranial space ultimately result in herniation of the brain, whenever there is a progressive rise in intracranial pressure (ICP). This hernia- tion may be symptomatic depending on the rapidity of ICP elevation and compensatory shifts in the rest of the occupants of the cranial cavity. Progressive herniation of the brain through dural defect is well recognized in the cases of growing skull fracture, specifically in the first decade of life. In these cases, the initial rise in ICP during head trauma results in protrusion of the brain through the dural defect, which is self- perpetuating under the special circum- stances dictated by a growing brain and the brain pulsations progressively sepa- rating the calvarial fracture fragments. However, we have seen an analogous phenomenon in adults who have under- gone an elective craniotomy for excision of brain tumors. It results in delayed neuro- logic deterioration. This interesting observation is exemplified by a case series highlighting the incipient nature of this herniation and its role in delayed neuro- logic deterioration. CASE 1 This 55-year-old female of African ethnicity was operated for a large parasagittal me- ningioma with worsening headaches and hemiparesis. The patient underwent a standard parasagittal craniotomy extending across midline for adequate exposure of the superior sagittal sinus. Tumor devascula- rization and subsequent excision were uneventful but toward the conclusion of surgery, the patient suffered from an unexplained transfusion reaction. This manifested as a sudden fall in blood pres- sure and necessitated rapid dural reconsti- tution with pericranial graft and subsequent closure of the wound. Due to the emergent nature of the closure in a hemodynamically unstable patient, water- tight dural approximation could not be achieved. After hemodynamic stabilization, the patient gradually recovered conscious- ness with no apparent motor deficit in the immediate postoperative period. However, on the fourth postoperative day, she had a generalized convulsion, which was aborted with routine anticonvulsant medications. She developed hemiparesis after the seizure, which worsened rapidly over 24 hours and prompted a magnetic resonance imaging (MRI) brain study (Figure 1). Imaging revealed herniation of the brain through the paramedian dural defect. She was offered surgical reexploration but declined. Her hemiplegia showed no improvement until her last follow-up almost 30 days after the surgery. She could not be contacted subsequently. - BACKGROUND: Herniation of the brain through an osseodural defect has been well described in small children as an uncommon occurrence after closed head injury. Pressure from the growing brain has been implicated in progressive enlargement and reshaping of the fracture line. An analogous phenomenon in adults has been observed in the described cases where neurosurgical inter- vention led to a persistent dural defect. Transcalvarial herniation of the brain through the dural defect resulted in characteristic neurologic and imaging findings producing symptoms disproportionately greater than expected from the extent of the affected brain, accompanied by enlargement of the underlying ventricle and elevation of the bone flap. Disruption of the axonal conduction due to distortion of the axons in the herniated brain is probably responsible for these observations. - CASE DESCRIPTION: A series of 3 cases is described. In all cases, the dural reconstitution at the conclusion of surgery was incomplete. Brain herniation was evident in the postoperative scan. The transcalvarial herniation of the brain was precipitated by either a seizure and resultant brain swelling or persistently raised intracranial tension from a tumor residual. In 2 cases, surgical reexplo- ration resulted in improvement in the neurologic symptoms. - CONCLUSIONS: In symptomatic patients with transcalvarial herniation of the brain, identified on imaging, the neurologic syndrome is quite characteristic. Recognition of this condition and prompt treatment lead to lasting neurologic improvement. Key words - Adult - Iatrogenic - Incipient - Transcalvarial herniation Abbreviations and Acronyms ICP: Intracranial pressure MRI: Magnetic resonance imaging Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India To whom correspondence should be addressed: Shashwat Mishra, M.Ch. [E-mail: smishra@aiims.edu] Citation: World Neurosurg. (2019) 130:240-243. https://doi.org/10.1016/j.wneu.2019.07.009 Journal homepage: www.journals.elsevier.com/world- neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved. 240 www.SCIENCEDIRECT.com WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.07.009 Case Report